EC |
1.3.1.51 |
Accepted name: |
2′-hydroxydaidzein reductase |
Reaction: |
2′-hydroxy-2,3-dihydrodaidzein + NADP+ = 2′-hydroxydaidzein + NADPH + H+ |
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For diagram of glyceollin biosynthesis (part 1), click here |
Other name(s): |
NADPH:2′-hydroxydaidzein oxidoreductase; HDR; 2′-hydroxydihydrodaidzein:NADP+ 2′-oxidoreductase |
Systematic name: |
2′-hydroxy-2,3-dihydrodaidzein:NADP+ 2′-oxidoreductase |
Comments: |
In the reverse reaction, the 2′-hydroxyisoflavone (2′-hydroxydaidzein) is reduced to an isoflavanone. Also acts on 2′-hydroxyformononetin and to a small extent on 2′-hydroxygenistein. Involved in the biosynthesis of the phytoalexin glyceollin. The isoflavones biochanin A, daidzein and genestein as well as the flavonoids apigenin, kaempferol and quercetin do not act as substrates. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 126125-01-7 |
References: |
1. |
Fischer, D., Ebenau-Jehle, C. and Grisebach, H. Phytoalexin synthesis in soybean: purification and characterization of NADPH:2′-hydroxydaidzein oxidoreductase from elicitor-challenged soybean cell cultures. Arch. Biochem. Biophys. 276 (1990) 390–395. [DOI] [PMID: 2306102] |
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[EC 1.3.1.51 created 1992, modified 2004] |
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EC
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1.14.13.86
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Deleted entry: | 2-hydroxyisoflavanone synthase. This enzyme was classified on the basis of an incorrect reaction. The activity is covered by EC 1.14.14.87, 2-hydroxyisoflavanone synthase |
[EC 1.14.13.86 created 2004, deleted 2013] |
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EC
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1.14.13.89
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Transferred entry: | isoflavone 2-hydroxylase. Now EC 1.14.14.90, isoflavone 2-hydroxylase
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[EC 1.14.13.89 created 2005, deleted 2018] |
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EC
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1.14.13.136
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Transferred entry: | 2-hydroxyisoflavanone synthase. Now EC 1.14.14.87, 2-hydroxyisoflavanone synthase
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[EC 1.14.13.136 created 2011, modified 2013, deleted 2018] |
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EC |
1.14.14.87 |
Accepted name: |
2-hydroxyisoflavanone synthase |
Reaction: |
(1) liquiritigenin + O2 + [reduced NADPH—hemoprotein reductase] = 2,4′,7-trihydroxyisoflavanone + H2O + [oxidized NADPH—hemoprotein reductase] (2) (2S)-naringenin + O2 + [reduced NADPH—hemoprotein reductase] = 2,4′,5,7-tetrahydroxyisoflavanone + H2O + [oxidized NADPH—hemoprotein reductase] |
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For diagram of daidzein biosynthesis, click here |
Glossary: |
liquiritigenin = 4′,7-dihydroxyflavanone
(2S)-naringenin = 4′,5,7-dihydroxyflavanone
2,4′,5,7-tetrahydroxyisoflavanone = 2-hydroxy-2,3-dihydrogenistein |
Other name(s): |
CYP93C; IFS; isoflavonoid synthase |
Systematic name: |
liquiritigenin, [reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (hydroxylating, aryl migration) |
Comments: |
A cytochrome P-450 (heme thiolate) protein found in plants. The reaction involves the migration of the 2-phenyl group of the flavanone to the 3-position of the isoflavanone. The 2-hydroxyl group is derived from the oxygen molecule. EC 4.2.1.105, 2-hydroxyisoflavanone dehydratase, acts on the products with loss of water and formation of genistein and daidzein, respectively. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB |
References: |
1. |
Kochs, G. and Grisebach, H. Enzymic synthesis of isoflavones. Eur. J. Biochem. 155 (1986) 311–318. [DOI] [PMID: 3956488] |
2. |
Hashim, M.F., Hakamatsuka, T., Ebizuka, Y. and Sankawa, U. Reaction mechanism of oxidative rearrangement of flavanone in isoflavone biosynthesis. FEBS Lett. 271 (1990) 219–222. [DOI] [PMID: 2226805] |
3. |
Steele, C. L., Gijzen, M., Qutob, D. and Dixon, R.A. Molecular characterization of the enzyme catalyzing the aryl migration reaction of isoflavonoid biosynthesis in soybean. Arch. Biochem. Biophys. 367 (1999) 146–150. [DOI] [PMID: 10375412] |
4. |
Sawada, Y., Kinoshita, K., Akashi, T., Aoki, T. and Ayabe, S. Key amino acid residues required for aryl migration catalysed by the cytochrome P450 2-hydroxyisoflavanone synthase. Plant J. 31 (2002) 555–564. [DOI] [PMID: 12207646] |
5. |
Sawada, Y. and Ayabe, S. Multiple mutagenesis of P450 isoflavonoid synthase reveals a key active-site residue. Biochem. Biophys. Res. Commun. 330 (2005) 907–913. [DOI] [PMID: 15809082] |
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[EC 1.14.14.87 created 2011 as EC 1.14.13.136, modified 2013, transferred 2018 to EC 1.14.14.87] |
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EC |
1.14.14.90 |
Accepted name: |
isoflavone 2′-hydroxylase |
Reaction: |
an isoflavone + [reduced NADPH—hemoprotein reductase] + O2 = a 2′-hydroxyisoflavone + [oxidized NADPH—hemoprotein reductase] + H2O |
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For diagram of the biosynthesis of formononetin and derivatives, click here |
Other name(s): |
isoflavone 2′-monooxygenase; CYP81E1; CYP Ge-3 |
Systematic name: |
isoflavone,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (2′-hydroxylating) |
Comments: |
A cytochrome P-450 (heme-thiolate) protein. Acts on daidzein, formononetin and genistein. EC 1.14.14.89, 4′-methoxyisoflavone 2′-hydroxylase, has the same reaction but is more specific as it requires a 4′-methoxyisoflavone. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 110183-49-8 |
References: |
1. |
Akashi, T., Aoki, T. and Ayabe, S.-I. CYP81E1, a cytochrome P450 cDNA of licorice (Glycyrrhiza echinata L.), encodes isoflavone 2′-hydroxylase. Biochem. Biophys. Res. Commun. 251 (1998) 67–70. [DOI] [PMID: 9790908] |
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[EC 1.14.14.90 created 2005 as EC 1.14.13.89, transferred 2018 to EC 1.14.14.90] |
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EC |
2.1.1.46 |
Accepted name: |
isoflavone 4′-O-methyltransferase |
Reaction: |
S-adenosyl-L-methionine + a 4′-hydroxyisoflavone = S-adenosyl-L-homocysteine + a 4′-methoxyisoflavone |
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For diagram of the biosynthesis of biochanin A, click here and for diagram of the biosynthesis of formononetin and derivatives, click here |
Other name(s): |
4′-hydroxyisoflavone methyltransferase; isoflavone methyltransferase; isoflavone O-methyltransferase |
Systematic name: |
S-adenosyl-L-methionine:4′-hydroxyisoflavone 4′-O-methyltransferase |
Comments: |
Requires Mg2+ for activity. The enzyme catalyses the methylation of daidzein and genistein. It does not methylate naringenin, apigenin, luteolin or kaempferol. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 55071-80-2 |
References: |
1. |
Wengenmayer, H., Ebel, J. and Grisebach, H. Purification and properties of a S-adenosylmethionine: isoflavone 4′-O-methyltransferase from cell suspension cultures of Cicer arietinum L. Eur. J. Biochem. 50 (1974) 135–143. [DOI] [PMID: 4452353] |
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[EC 2.1.1.46 created 1976, modified 2011] |
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EC |
2.1.1.150 |
Accepted name: |
isoflavone 7-O-methyltransferase |
Reaction: |
S-adenosyl-L-methionine + a 7-hydroxyisoflavone = S-adenosyl-L-homocysteine + a 7-methoxyisoflavone |
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For diagram of the biosynthesis of formononetin and derivatives, click here and of biochanin A, click here |
Systematic name: |
S-adenosyl-L-methionine:hydroxyisoflavone 7-O-methyltransferase |
Comments: |
The enzyme from alfalfa can methylate daidzein, genistein and 6,7,4′-trihydroxyisoflavone but not flavones or flavanones. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 136111-54-1 |
References: |
1. |
Edwards, R. and Dixon, R.A. Isoflavone O-methyltransferase activities in elicitor-treated cell suspension cultures of Medicago sativa. Phytochemistry 30 (1991) 2597–2606. |
2. |
He, X.Z. and Dixon, R.A. Genetic manipulation of isoflavone 7-O-methyltransferase enhances biosynthesis of 4′-O-methylated isoflavonoid phytoalexins and disease resistance in alfalfa. Plant Cell 12 (2000) 1689–1702. [PMID: 11006341] |
3. |
He, X.-Z. and Dixon, R.A. Affinity chromatography, substrate/product specificity, and amino acid sequence analysis of an isoflavone O-methyltransferase from alfalfa (Medicago sativa L.). Arch. Biochem. Biophys. 336 (1996) 121–129. [DOI] [PMID: 8951042] |
4. |
He, X.Z., Reddy, J.T. and Dixon, R.A. Stress responses in alfalfa (Medicago sativa L). XXII. cDNA cloning and characterization of an elicitor-inducible isoflavone 7-O-methyltransferase. Plant Mol. Biol. 36 (1998) 43–54. [PMID: 9484461] |
5. |
Liu, C.-J. and Dixon, R.A. Elicitor-induced association of isoflavone O-methyltransferase with endomembranes prevents the formation and 7-O-methylation of daidzein during isoflavonoid phytoalexin biosynthesis. Plant Cell 13 (2001) 2643–2658. [DOI] [PMID: 11752378] |
6. |
Zubieta, C., He, X.-Z., Dixon, R.A. and Noel, J.P. Structures of two natural product methyltransferases reveal the basis for substrate specificity in plant O-methyltransferases. Nat. Struct. Biol. 8 (2001) 271–279. [DOI] [PMID: 11224575] |
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[EC 2.1.1.150 created 2003] |
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EC |
2.1.1.154 |
Accepted name: |
isoliquiritigenin 2′-O-methyltransferase |
Reaction: |
S-adenosyl-L-methionine + isoliquiritigenin = S-adenosyl-L-homocysteine + 2′-O-methylisoliquiritigenin |
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For diagram of daidzein biosynthesis, click here |
Glossary: |
isoliquiritigenin = 4,2′,4′-trihydroxychalcone |
Other name(s): |
chalcone OMT; CHMT |
Systematic name: |
S-adenosyl-L-methionine:isoliquiritigenin 2′-O-methyltransferase |
Comments: |
Not identical to EC 2.1.1.65, licodione 2′-O-methyltransferase [2]. While EC 2.1.1.154, isoliquiritigenin 2′-O-methyltransferase can use licodione as a substrate, EC 2.1.1.65 cannot use isoliquiritigenin as a substrate. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 139317-14-9 |
References: |
1. |
Maxwell, C.A., Edwards, R. and Dixon, R.A. Identification, purification, and characterization of S-adenosyl-L-methionine: isoliquiritigenin 2′-O-methyltransferase from alfalfa (Medicago sativa L.). Arch. Biochem. Biophys. 293 (1992) 158–166. [DOI] [PMID: 1731632] |
2. |
Ichimura, M., Furuno, T., Takahashi, T., Dixon, R.A. and Ayabe, S. Enzymic O-methylation of isoliquiritigenin and licodione in alfalfa and licorice cultures. Phytochemistry 44 (1997) 991–995. [DOI] [PMID: 9055445] |
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[EC 2.1.1.154 created 2004] |
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EC |
2.1.1.212 |
Accepted name: |
2,7,4′-trihydroxyisoflavanone 4′-O-methyltransferase |
Reaction: |
S-adenosyl-L-methionine + 2,4′,7-trihydroxyisoflavanone = S-adenosyl-L-homocysteine + 2,7-dihydroxy-4′-methoxyisoflavanone |
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For diagram of daidzein biosynthesis, click here |
Other name(s): |
SAM:2,7,4′-trihydroxyisoflavanone 4′-O-methyltransferase; HI4′OMT; HMM1; MtIOMT5; S-adenosyl-L-methionine:2,7,4′-trihydroxyisoflavanone 4′-O-methyltransferase |
Systematic name: |
S-adenosyl-L-methionine:2,4′,7-trihydroxyisoflavanone 4′-O-methyltransferase |
Comments: |
Specifically methylates 2,4′,7-trihydroxyisoflavanone on the 4′-position. No activity with isoflavones [2]. The enzyme is involved in formononetin biosynthesis in legumes [1]. The protein from pea (Pisum sativum) also methylates (+)-6a-hydroxymaackiain at the 3-position (cf. EC 2.1.1.270, (+)-6a-hydroxymaackiain 3-O-methyltransferase) [4]. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB |
References: |
1. |
Akashi, T., Sawada, Y., Shimada, N., Sakurai, N., Aoki, T. and Ayabe, S. cDNA cloning and biochemical characterization of S-adenosyl-L-methionine: 2,7,4′-trihydroxyisoflavanone 4′-O-methyltransferase, a critical enzyme of the legume isoflavonoid phytoalexin pathway. Plant Cell Physiol. 44 (2003) 103–112. [PMID: 12610212] |
2. |
Deavours, B.E., Liu, C.J., Naoumkina, M.A., Tang, Y., Farag, M.A., Sumner, L.W., Noel, J.P. and Dixon, R.A. Functional analysis of members of the isoflavone and isoflavanone O-methyltransferase enzyme families from the model legume Medicago truncatula. Plant Mol. Biol. 62 (2006) 715–733. [DOI] [PMID: 17001495] |
3. |
Liu, C.J., Deavours, B.E., Richard, S.B., Ferrer, J.L., Blount, J.W., Huhman, D., Dixon, R.A. and Noel, J.P. Structural basis for dual functionality of isoflavonoid O-methyltransferases in the evolution of plant defense responses. Plant Cell 18 (2006) 3656–3669. [DOI] [PMID: 17172354] |
4. |
Akashi, T., VanEtten, H.D., Sawada, Y., Wasmann, C.C., Uchiyama, H. and Ayabe, S. Catalytic specificity of pea O-methyltransferases suggests gene duplication for (+)-pisatin biosynthesis. Phytochemistry 67 (2006) 2525–2530. [DOI] [PMID: 17067644] |
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[EC 2.1.1.212 created 2011] |
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EC |
2.1.1.231 |
Accepted name: |
flavonoid 4′-O-methyltransferase |
Reaction: |
S-adenosyl-L-methionine + a 4′-hydroxyflavanone = S-adenosyl-L-homocysteine + a 4′-methoxyflavanone |
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For diagram of naringenin methyl ethers biosynthesis, click here |
Glossary: |
naringenin = 4′,5,7-trihydroxyflavan-4-one |
Other name(s): |
SOMT-2; 4′-hydroxyisoflavone methyltransferase |
Systematic name: |
S-adenosyl-L-methionine:flavonoid 4′-O-methyltransferase |
Comments: |
The enzyme catalyses the 4′-methylation of naringenin. In vitro it catalyses the 4′-methylation of apigenin, quercetin, daidzein and genistein. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc |
References: |
1. |
Kim, D.H., Kim, B.G., Lee, Y., Ryu, J.Y., Lim, Y., Hur, H.G. and Ahn, J.H. Regiospecific methylation of naringenin to ponciretin by soybean O-methyltransferase expressed in Escherichia coli. J. Biotechnol. 119 (2005) 155–162. [DOI] [PMID: 15961179] |
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[EC 2.1.1.231 created 2011] |
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EC |
2.3.1.170 |
Accepted name: |
6′-deoxychalcone synthase |
Reaction: |
3 malonyl-CoA + 4-coumaroyl-CoA + NADPH + H+ = 4 CoA + isoliquiritigenin + 3 CO2 + NADP+ + H2O |
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For diagram of daidzein biosynthesis, click here |
Glossary: |
isoliquiritigenin = 4,2′,4′-trihydroxychalcone
liquiritigenin = 7,4′-dihydroxyflavanone |
Systematic name: |
malonyl-CoA:4-coumaroyl-CoA malonyltransferase (cyclizing, reducing) |
Comments: |
Isoliquiritigenin is the precursor of liquiritigenin, a 5-deoxyflavanone. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 114308-23-5 |
References: |
1. |
Ayabe, S., Udagawa, A. and Furuya, T. NAD(P)H-dependent 6′-deoxychalcone synthase activity in Glycyrrhiza echinata cells induced by yeast extract. Arch. Biochem. Biophys. 261 (1988) 458–462. [DOI] [PMID: 3355160] |
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[EC 2.3.1.170 created 2004] |
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EC |
2.4.1.170 |
Accepted name: |
isoflavone 7-O-glucosyltransferase |
Reaction: |
UDP-glucose + an isoflavone = UDP + an isoflavone 7-O-β-D-glucoside |
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For diagram of the biosynthesis of biochanin A, click here and for diagram of the biosynthesis of formononetin and derivatives, click here |
Other name(s): |
uridine diphosphoglucose-isoflavone 7-O-glucosyltransferase; UDPglucose-favonoid 7-O-glucosyltransferase; UDPglucose:isoflavone 7-O-glucosyltransferase |
Systematic name: |
UDP-glucose:isoflavone 7-O-β-D-glucosyltransferase |
Comments: |
The 4′-methoxy isoflavones biochanin A and formononetin and, more slowly, the 4′-hydroxyisoflavones genistein and daidzein, can act as acceptors. The enzyme does not act on isoflavanones, flavones, flavanones, flavanols or coumarins. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 97089-62-8 |
References: |
1. |
Köster, J. and Barz, W. UDP-glucose:isoflavone 7-O-glucosyltransferase from roots of chick pea (Cicer arietinum L.). Arch. Biochem. Biophys. 212 (1981) 98–104. [DOI] [PMID: 6458246] |
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[EC 2.4.1.170 created 1989] |
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EC |
4.2.1.105 |
Accepted name: |
2-hydroxyisoflavanone dehydratase |
Reaction: |
(1) 2,4′,7-trihydroxyisoflavanone = daidzein + H2O (2) 2,4′,5,7-tetrahydroxyisoflavanone = genistein + H2O |
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For diagram of biochanin A biosynthesis, click here and for diagram of daidzein biosynthesis, click here |
Glossary: |
daidzein = 4′,7-dihydroxyisoflavone
genistein = 4′,5,7-dihydroxyisoflavone |
Other name(s): |
2,7,4′-trihydroxyisoflavanone hydro-lyase; 2,7,4′-trihydroxyisoflavanone hydro-lyase (daidzein-forming) |
Systematic name: |
2,4′,7-trihydroxyisoflavanone hydro-lyase (daidzein-forming) |
Comments: |
Catalyses the final step in the formation of the isoflavonoid skeleton. The reaction also occurs spontaneously. |
Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 166800-10-8 |
References: |
1. |
Hakamatsuka, T., Mori, K., Ishida, S., Ebizuka, Y and Sankawa, U. Purification of 2-hydroxyisoflavanone dehydratase from the cell cultures of Pueraria lobata. Phytochemistry 49 (1998) 497–505. |
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[EC 4.2.1.105 created 2004, modified 2013] |
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EC |
5.5.1.6 |
Accepted name: |
chalcone isomerase |
Reaction: |
a chalcone = a flavanone |
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For diagram of daidzein biosynthesis, click here and for diagram of flavonoid biosynthesis, click here |
Other name(s): |
chalcone-flavanone isomerase; flavanone lyase (decyclizing) |
Systematic name: |
flavanone lyase (ring-opening) |
Links to other databases: |
BRENDA, EXPASY, GTD, KEGG, MetaCyc, PDB, CAS registry number: 9073-57-8 |
References: |
1. |
Moustafa, E. and Wong, E. Purification and properties of chalcone-flavanone isomerase from soya bean seed. Phytochemistry 6 (1967) 625–632. |
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[EC 5.5.1.6 created 1972] |
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